In a rotary machining tool used for boring, shaping, or the like it is standard to mount the tool changer on the back of the machine, an arrangement that substantially complicates the movements for tool changing and that also makes the machine more expensive. Similarly providing the changer on the side of the apparatus necessitates a transfer device between the changer and the chuck of the spindle that can only operate when the chuck is moved into a special transfer position.
In another known arrangement the tool magazine is mounted between two columns of the machine frame centrally in the machine and the entire magazine is moved into a position aligned with the spindle of the machine. When thus positioned a tool can be taken out of the chuck by the magazine, then another moved into place and put into the chuck. In this arrangement also, however, the spindle must move with the chuck into an intermediate transfer position, one that is relatively far from its working position. In this intermediate position the chuck must be lifted sufficiently to clear even the longest tool that might be mounted in it, so that as a rule the spindle is moved into its uppermost position for such tool changing. Moving up and down between this high position and the working position wastes considerable time, adding to delays in a production line where such a rotary machine with automatic tool changing is typically used.
Yet another system mounts the tool magazine on the vertically displaceable spindle. Thus in theory in any position of the spindle it is possible to change tools. Since the magazine must be concentric to the axis of the tool spindle, with the tools hanging from it, substantial space must be provided to accommodate tools of different lengths. In addition it is necessary to provide a separate pivotal transfer device for each tool, and roller bearings rotatably support each of these transfer devices. The changing device is therefore very expensive, and special tools must be used with it, so that the entire system is extremely costly.